Iono, I'd say Liberty Prime would win after a long fight. Liberty Prime does have this laser eye beams that is similar to Iron Man's hand blast. However, Liberty Prime also has mini nukes, from which I really doubt Iron Man's suit can withstand. Although Iron man does have speed, I still think Liberty Prime would win.
Also, if Liberty Prime gets his hands on Iron Man, he might just suck the energy out of Iron Man like he did to the force fields.